1. Field of the Invention
The present invention is directed to an intermetallic compound. More specifically, the instant invention is directed to a new intermetallic compound useful in the catalytic polymerization of alpha-olefins.
2. Background of the Prior Art
The ever increasing body of technical literature, especially patents, directed to catalysts useful in the polymerization of unsaturated monomers in general and alpha-olefins in particular evidences the tremendous interest and importance of this technology. Much work has been devoted to the development of new catalysts which comprise a transition metal such as titanium, vanadium, zirconium or the like in combination with a metal such as magnesium, manganese and the like. As those skilled in the art are aware, utilization of this type of catalyst in combination with an organometallic compound, the metal of which is preferably aluminum, is utilized as a catalyst system in the polymerization of alpha-olefins.
The voluminous nature of the prior art directed to this technology makes it impossible to fully summarize the scope of just recent developments. Thus, only the most relevant prior art is included in the following discussion of catalysts and methods of forming catalysts useful in the polymerization of ethylenically unsaturated monomers.
Of particular interest is U.S. Pat. No. 4,451,688 which discloses a process for preparing a polyolefin in presence of a catalyst, the catalyst comprising the combination of (I) a solid substance obtained by reacting (i) at least one magnesium compound represented by the general formula R.sup.1.sub.m (OR.sup.2).sub.n MgX.sub.2-(m+n) wherein R.sup.1 and R.sup.2 are each a hydrocarbon radical having 1 to 24 carbon atoms; X is halogen; m is 0 to 2; n is 0 to 2 provided that the sum of m and n is between 0 and 2 with (ii) a titanium and/or vanadium compound; (II) a silicon compound having the general formula R'.sub.m Si(OR").sub.n X.sub.4-(m+n) wherein R' and R" are each hydrocarbon radicals having 1 to 24 carbon atoms; X is a halogen; m is 0 to 4; n is greater than 0 but not more than 4 with the proviso that the sum of m and n is greater than 0 but not more than 4; and (III) an organometallic compound. The '688 patent includes the further limitation that the silicon compound (II) be pre-reacted with the organometallic compound (III).
Another recent disclosure of a process for polymerizing an alpha-olefin, embodied in U.S. Pat. No. 4,365,048, utilizes a catalyst comprising a Grignard compound of the formula R.sup.3 MgX, wherein R.sup.3 is an alkyl having 1 to 8 carbon atoms; and X is a halogen, is reacted with the reaction product of an aluminum halide with an organic silicon compound of the formula R.sup.1.sub.n Si(OR.sup.2).sub.4-n, wherein R.sup.1 is an alkyl having 1 to 8 carbon atoms or phenyl; R.sup.2 is an alkyl of 1 to 8 carbon atoms; and n is 1, 2 or 3. The resultant solid reaction product is contacted with titanium tetrahalide. The resulting titanium-containing solid product is treated with an organic acid ester and, finally, the so-treated solid product is contacted with a titanium tetrahalide. The catalyst system not only includes the product of the above-mentioned steps but, in addition, the reaction product includes a trialkylaluminum compound where the alkyl is one of 2 to 6 carbon atoms.
Yet another recent teaching is U.S. Pat. No. 4,374,753. This patent discloses a catalyst and a method in which the catalyst is used in association with an aluminum cocatalyst in the polymerization and copolymerization of alpha-olefins. The catalyst of this patent is prepared by reacting an organic silicon compound with silica and/or alumina having surface hydroxyl groups. The silicon compound reacts with the hydroxyl groups. The product of this reaction is, in turn, reacted with an organometallic compound wherein the metal thereof is one of Group IIb of the Periodic Table, preferably an organomagnesium compound. The product of this reaction is then reacted with an alcohol. Finally, this reaction product is reacted with a halide or alkoxide of titanium, vanadium, zirconium or mixtures thereof.
Although these recent disclosures advance the art, there is still a growing need for new improved catalysts in the polymerization of alpha-olefins in general and ethylene homopolymers and copolymers in particular. Specifically, there is a continuing need to prepare polymers having narrower molecular weight distribution with reduced amounts of low molecular weight polymer than those presently known in the art.